Feeding mechanism for roasting furnaces



May 10, 1932- I R. c. KUNKEL 1,857,919

FEEDING MECHANISM FOR ROASTING FURNACES Fild Maron 8, 1929 RICHARD/l/umrEL Patented May 10, 1932 teren STATES PATENT; "iol-FICE RICHARDCOOPER KUN KEL, OF PULASKI, VRGINIA, ASSIGNOR TO GENERAL CHEMICALCOMPANY, OF NEW YORK, N. Y., .A CORPORATION OF NEW YORK z FEEDING-MECHANISM FOR ROASTING FURNACES Application mea March s, '1929. serialNo. 345,325.

This invention relates to furnaces for roasting granular material suchfor example as ore and the like, and is especially concernedwith thefeeding of the granular material to the furnace. 'Such roasting furnacesare provided with stationary hearths upon which the ore is stirred anddistributed by rakes or ploughs aflixed to a rotating arm. The ore isfed in at the topof the furnace to the uppermost hearth and proceedsdownwardly from hearth to hearth in its progress through the furnace.

It is desirable that the ore or other granu- I lar material be fed tothe furnace periodical-y ly and in regulatable quantities, and it isimportant that it be admitted to the furnace without the admission ofair when the apparatus is operating under a negative draft and toeliminate the loss of furnace gases when the apparatus is operatingunder a positive draft. It is also important that the apparatus becapable of ready adjustment and be so designed that it is notaffected'by corrosion caused bythe gases within the furnace.

Roasting furnaces have heretofore been provided with feeding mechanismsof lcomplicated design, expensive in first cost and in upkeep, and whichmoreover have not been provided with proper means for preventing theentrance of air or the escape of furnace gases. In some of these formerfeed mechanisms also the working parts soon became badly worn eitherthrough mechanical wear or corrosion, and because of theircomparativeinaccessibility it has been difficult to replace such parts.

The present invention is directed to the overcoming of such diiicultiesas these, and it has for its principal object the provision of a feedmechanism which will provide a positive gas seal without the use ofcomplicated mechanism.`

Another object of the invention is to provide a feeding mechanism whichwill supply the ore to the furnace periodically at a uniform rate, thatis, although the ore is fed to the furnace inbatches ratherthancontinuously, nevertheless the amount of materiai in each batch issubstantially the same.

A further object of the invention is the provision of a feedingmechanism which is so. constructed that 1t 1s easy of access and easy toadjust;

Another object of the invention is to prol duce a feedingmechanisnrwhich is low in first cost of installation, which is notsubject.,

The preferred embodiment of the invene,

tive idea is shown in the accompanying drawings, in which,

Fig. 3 is a somewhat enlarged section taken.` through the ore admissionvalve.

Referring now to the accompanying drawings, the furnace comprises acylindrical casing 10 provided with a series of superposed floors, ofwhich onlyk two are shown and in k dicated in Fig. 1 by the referencecharacters 11 and 12, the floors being alternately provided withapertures 13 at the periphery and apertures 14 at the center. Thefurnace is provided with a roof 15, and the floors'll).

and 12, together with the similar floors be# low them, constitute vtheburning hearths. rfhe gaseous products pass out through an opening (notshown) in the cylindrical walll() above the uppermost floor 11.

Extending vertically through the center of vthe furnaceis a rotatableshaft 16, to which is affixed a plurality of horizontally extendingstirrer or rabble arms 17 and 18. The arms 17 are providedy withdefiecting projections 19, which work the ore towards' the peripheralopenings 13', and arms 18 have similar projections 2O arranged to workthe ore in an opposite direction towards the central. aperture 14;

The ore is fedto the furnace through the 32 adjustable.

per 2l will descend onto shelf. 23 until the pile reaches the lower edgeof the mouth. The mouth 22 is vertically adjustable by means (not shown)so as to vary the elevationof itslower surface with respect to the shelf23 and in this way regulate the size of the pile of ore on the shelf.

There is an aperture in the roof l5 of the furnace at one side of theshelf 23, as may be seen in Fig. 2, yand in this aperture there isplaced a cylindrical member 24 preferably 'of cast iron. Cylindricalmember 24 is pro l vided with a deep recess or pocket 25 on its upperside, and m the bottom of the member there is a conical valve opening26. A heavy conical-shaped valve plug 27, also preferably of cast iron,fits the valve opening 26, and is adapted to be raised and lowered bymeans of a stem 28, which is attached to the end of a lever 29 fulcrumedat 30 to a bar 3l preferably bolted or otherwise securedv to thecylindrical member 24.

A blade or sweep member 32 is mounted upon a bracket 33 secured to theupper portion of rotating shaft 16. This mounting comprises a pair ofbolts 34 passing through a slot 35 so as to make the position of bladeThe rotationV of shaft 1 6 in the direction of the arrow shown in F 1g.2

causes blade 32 to sweep ore from the pile on shelf 23 into the pocket25 of the cylindrical member 24.

The free. end-of lever 29 is curved upwardly as shown in Fig. 3 into thepath of the blade 32, so that shortly after blade 32 has swept the oreinto the kpocket 25, blade 32 engages the lever 29 and causes the valveplug 27 to be automatically raised so that the ore in the pocket 25 runsthrough the valve open-` ing 26 onto the upper shelf l1 of the furnace.As soon as the blade 32 passes the upturned end of lever 29, the valveplug 27 again drops into the valve opening. p If blade 32 is notof' theright width, or if the blade rotates vtoo fast, the valve plug 27 willdrop into the valve opening before all of the ore which has been sweptinto the pocket 25 has had a chance to pass into the roaster. This isadjusted however' by loosening the bolts 34 and adjusting blade 32 sothat it will sweepless ore from the shelf 23 into the pocket. In otherwords, the radius of the circular path of the outer end of the blade asindicated by the dotted line in Fig. 2, is decreased. If it is desiredto increase the amount of ore fed to the roaster, additional blades 32may be mounted upon shaft 16, or if desired one or more additionalhoppers 21 as indicated by the dotted lines in Figs. l and 2, may beused. The progress of the ore from hearth tov heart through the furnacedepends however upon the spe-ed'of rotation of shaft l6,and with thefeeding mechanism of the present invention, the rate at which the ore isfed to the roastcr or furnace depends directly upon the speed ofrotation of this same shaft. Hence the ore automatically is fed in atthe top of the roaster at a rate corresponding to its progress throughthe apparatus.

The rate at which the ore can be roasted in the furnace isdetermined bythe area of the superposed floors which4 constitute the burning hearths,and the speed of the rabble arms 17. It is therefore an easy matter tomaire the valve opening 26 of the proper size and the blade 32 of theproper lwidth to cause the feeding mechanism to supply the proper amountof ore for any given furnace.

it will be understood that in the operation of the ore feedingmechanism, the blade 32 first sweeps a quantity of ore into the pocketbefore the valve plug 27 is raised so that at the time this occurspocket 25 is filled with ore co'xf'ering the valve plug and opening asshown in l. riherefore as the valve is opened, the ore pile in pocket 25immediately begins to flow down through the opening 26. rl'he quanity ofore inthe pocket 25 is adjusted as previously described so that the plugfalls into the valve opening just as the last of the ore pile runsthrough the opening 26. Illhe plug remains in its seat until anotherquantity of ore has been swept into the pocket 25. rhe feeding mechanismtherefore provides a positive gas seal at all times except' vhcn the oreis actually running through the entrance opening 26 and during this timethe flow of the ore itself provides a comparatively effective seal.Hence if the pressure on the interior of the furnace is less than thatof the atmosphere, as is the casewhen the furnace operating under aminus or negative draft, it is impossible for any appreciable amount ofair to enter the furnace, and similarly the furnace gases are preventedfrom escaping when the pressure within the furnace is greater than thatof the atmosphere.

Another advantage of my improved feeding inecnanism is that it providesa sharp cut-off of the flow of ore into the furnace because after theore within the pocket has been discharged through the opening 26 and thevalve plug 27 comes down to its seat, it impossible for any further oreto enter until the plug is again raised. in a number of the feedingmechanisms of the prior art, the stopping of the flow of ore is notpositive and the ore continues to enter the furnace after the mechanismhas operated to cut off the supply. This isa disadvantage because lconstruction, and also as it is easyof access,

it can be replaced at low cost.

. The cylindrical member 24 is of sufficient diameter and depth so thatthe pocket 25 will hold the desired amount of ore, and by plac-V ingtheconical valve opening 26 slightly to one side of the center, theentire valve and valve operating mechanismV is made as a uni.

tary structure so that if it is necessary or desirable to make areplacement the entire mechanism can be readily removed simply bylifting the member 24 out of its seat in the feeding hole in the roof ofthe furnace.` Then another valve mechanism can be quickly inserted inits place and hence the change can be made without interruption in theoperation of the roaster.

In order to facilitate the insertion and removal of the valve mechanism,the body 3G of the cylindrical member 24 is made with a fairly quicktaper and the feed hole is correspondingly tapered. Also a ange 37 isprovided at the upper periphery of the member 24. Member 24 is hence asort of pot shaped casting which can be easily placed in or moved fromthe feed hole and engages the surfaces of the feed hole so as to make atight seal and so as to hold the casting firmly in position against thetendency to displace the same caused by the coaction of blade 32 withlever 29.

The foregoing is considered to be an eX- emplifying disclosure of thefeeding mechanism of my invention, and the invention includes suchmodifications as come `within f the scope of the appended claims.

I claim l. In a roasting furnace having a feed opening, a closure forthe feed opening, means including a movable sweep for periodicallydepositing in the vicinity of the opening so as to be held back by theclosure a quantity of granular material to be treated in the furnace,positively `operated means actuated cinity of the opening so as to beheld back by ltimes against the passage of gas.

the closure a quantity of granular material to be treated in thefurnace, and'means actuated by said shaft synchronouslywith theperiodical deposition of the granular material for opening the closureto allow the material to pass through the feed opening into vthefurnace, and closingthe closure when the flow of the materialtherethrough is substantially completed. n -v 3. A roasting furnacehaving a feed open'-` ing comprising a member having a pocket thereinfor'holding a quantity of granular material to be fed to the furnace,the member having an aperture in the bottom of the pocket, a valve plugseated in the aperture, means for periodically depositing material inthe pocket, means for raising the valve plug against the pressure oftheimaterial in the pocket to allow1 said material to` run, through theaperture into the furnace, land means for lowering thevalve plug andclosing the aperture substantially simultaneously with the completion ofthe iow of said material, whereby said aperture is sealed at V4. In `aroasting furnace having a feed opening, the combination of a fixed shelfdisposed near thel feed opening, a closure for said opening, means forperiodically transferring a quantity of material from the shelf into thevicinity of the feed opening, means actuated synchronously with theperiodical transfer of material from the shelf for opening the closureto permit the material to pass y. through the opening into the furnace,and means for closing the closure immediately thereafter.

5. In a roasting furnace having a feed opening and a rotating shaft, thecombina;`

tion of a shelf disposed near the feedopening, a closure for saidopening, meansY actuated by said shaft for periodicallytransferring aquantity of material 'from theV shelf to the vicinity of the feedopening, means actu-H ated by said shaft for opening the closure topermit the material to pass through the feed opening into the furnace,and means actu'- ated by the shaft for closing the closure substantiallysimultaneously with the completion of the flow of the material throughthe' feed opening.

6. A roasting furnace having a feed opening provided with a pocketsurrounding the same, a shelfvdisposed above and at one side of the feedopening, a closurefor said opening, means for periodically sweeping aquantity of granular material from the shelf into the Vpocket of thefeed opening, means for periodically openingthe closure against thepressure of said material to permit the material to pass through theopening into the furnace, and means for periodically closing 'theclosure approximatelyV at the end of the flow of said quantity ofmaterial. A Y

7. A roastingvfurnace having a feed open- .ing in the roof thereof, :arotating vertical when the flow .of the material is completed.

8. A roasting furnace having a feed open- :ing inthe roof1 thereofaud arotating shaft extending upwardly from the roof, a shelr disposed aboveand .at .one side of the feedy opening, a hopper having a dischargemouth disposed somewhatabove the surface of said Shelf so .as .toVmaintain a substantially constant supply ofgranular material on theshelf. to be fed to the furnace, .a closure for the feed opening, ablade fixed to the rotating shaft and `adapted to .move over the surfaceof the table below said discharge mouth and periodically sweep aquantity of the granular material from the shelf into a positioncovering the closure and the feed opening, means on the shaft foropening .the closure against the pressure of the .granular material.,and means also on the .shaft for lclosing the closure substantially assoon as the quantity of material has run through .the opening into thefurnace..

9. A roasting .furnace having a. feed opening in the roof thereof and arotating .shaft extending upwardly from the roof, a shelf kdisposedabove and at one side of the feed opening, a closure for said opening, ablade fined .to rotate with Said shaft .and move over said shelf andsweep :a quantity of granular material therefrom into the vicinity ofthe feed opening .and cover the closure therefor, and means actuated bysaid blade for opening the closure against the pressure of the materialand causing the closure to close the feed opening substantially as soonas the quantity of material has run through the feed opening -into thefurnace.

10. A roasting furnace having a feed opening in the roof thereof and arotating shaft extending upwardly from'the roof, a shelf disposed aboveand at one side of the feed opening, a vertically movable plug forclosing the feed opening, a pivoted lever for raising the plug out ofthe opening, a blade 'secured to said rotating shaft and adapted to passover the shelf and sweep therefrom a quantity of material on andsurrounding the plug While it remains in closed position, said pivotedlever having a cam surface extending into the path of said blade andadapted .to be engaged thereby after the blade has passed the shelf andraise the plug against the pressure of the material, the plug fallingunder the linfluence of gravity after the blade has passed said camsurface and there- :by Aclosing the feed opening after the matcri-al haspassed therethrough to the furnace.

1l. In a feeding mechanism for roasting furnaces, a unitary feedingdevice for insertion lin the feed .opening of the furnace comprising amember having a pocket in the upper side thereof, a feed opening in thebottom thereof, a vertically movable plug for closing said feed opening,and a lever for raising said plug .out of the feed opening fulcrumed `tothe side of said member.

12. In a roast-ing furnace having a rotating shaft andv a feed opening,a shelf posi- .tioned above and at one sideof said feed same time thatthe valve plug is lowered to P close the opening.

RXGHARD [COOPER KUNKEL.

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